The Arleigh Burke-class guided-missile destroyer USS Fitzgerald. damaged by colliding with a Philippine-flagged merchant vessel. is seen off Shimoda, Japan in this photo taken by Kyodo on June 17, 2017. (Kyodo/via REUTERS)

The U.S. Navy destroyer, USS Fitzgerald, maintained its collision course despite light signals from Philippine container ship ACX Crystal, leading to a crash of the two vessels, according to a report by the cargo ship’s captain reviewed by Reuters.

The crash killed seven U.S. sailors in clear weather south of Tokyo Bay at 1:30 a.m. on June 17.

The sailors were in their berthing compartments and their commander was injured in his cabin, suggesting no alarm was sounded.

Damage to the guided missile destroyer USS Fitzgerald is seen as the vessel is berthed at its mother port in Yokosuka, southwest of Tokyo, on June 18, 2017. (Kazuhiro Nogi/AFP/Getty Images)

ACX Crystal signaled to Fitzgerald with flashing lights to warn it about the coming collision and then steered sharply right, but failed to avoid the collision, according to a report by Crystal’s Captain Ronald Advincula to the ship’s Japanese owner Dainichi Investment Corporation. Reuters gleaned the report but could not verify it.

Both U.S. and Japanese Coast Guard as well as the U.S. Navy, Philippine government, and the Japan Transport Safety Board are investigating the crash and have refused media requests for comments.

It was the deadliest incident involving a U.S. Navy ship since the USS Cole was bombed in Yemen’s Aden harbor in 2000.

It is not clear how Fitzgerald could have miss a ship three times its size. Questions remain on Crystal’s side too. Japan’s Coast Guard stated it was notified about the crash by Crystal at 2:25 a.m.—almost an hour after the crash.

Damage on the Philippine-flagged container ship ACX Crystal after it collided with the guided missile destroyer USS Fitzgerald sails into Tokyo bay on June 17, 2017. (Kazuhiro Nogi/AFP/Getty Images)

Captain Advincula stated in the report that there was confusion on his ship’s bridge and that it only turned around and returned to the crash site after having continued on its course for another 7 miles.